1. Technical Field
The present invention relates to an imaging device configured to point an internal camera incorporated in a camera head toward a subject set in an imaging area and take an image of the subject.
2. Related Art
These imaging devices are roughly classified into two groups having different structures, one structure equipped with a stage for holding a subject mounted thereon and the other structure without such a stage. Various arrangements and applications have been proposed for the latter structure, because of its advantages, the small size, the light weight, and the easiness of handling (see, for example, JP-A-2007-194884).
In the prior art imaging device disclosed in the above cited reference, a subject is placed on an upper surface of, for example, a table or a disk, and a camera head is extended from a base located on a lateral side of an imaging area and is held over the imaging area by means of an arm structure. While images of the subject are taken with an internal camera incorporated in the camera head held over the imaging area, the imaging point may be changed by moving the subject according to the requirements. For example, there may be a desire to change the imaging point from a central area of the subject to any of upper and lower end areas and lateral side areas of the subject. Such a change of the imaging point requires a vertical sliding motion (upward or downward) of the subject or a horizontal sliding motion (leftward or rightward) of the subject. The imaging area of the camera may be narrower than the surface area of a subject, such as a large-size sheet or a long sheet. In this case, there is similarly a requirement for the vertical sliding motion (upward or downward) or the horizontal sliding motion (leftward or rightward) of the subject.
In one example, a certain subject, etc, a sheet, having substantially similar dimensions to those of the imaging area of the camera may be placed on the upper surface of the table or the disk, and the base may be located on an upper side of the sheet. The imaging area of the camera head held on the base by the arm structure covers the whole area of the sheet. The imaging point is then set on the center of the sheet. In this state, the base is located neither on the left side of the sheet nor on the right side of the sheet. This arrangement allows for the horizontal sliding motion (leftward or rightward) of the sheet to change the imaging point across the left-to-right width of the sheet. The positional change of the imaging point from the upper side to the lower side of the sheet, however, causes the sheet to interfere with the base located on the upper side of the sheet.
Such interference undesirably restricts the vertical sliding motion of the sheet (upward or downward) and limits the coverage of the imaging area in the vertical direction. When the base is located on the left side or on the right side of the sheet, on the other hand, the sheet is slidable in the vertical direction (upward or downward) without interfering with the base. While enabling the imaging point to be changed across the top-to-bottom length of the sheet, this arrangement undesirably restricts the horizontal sliding motion of the sheet (leftward or rightward) and limits the coverage of the imaging area in the horizontal direction. This discussion is similarly applicable to the case of taking images of a large-size sheet or a long sheet.